dmd.expression: Use align(8) for alignment of UnionExp

[ibuclaw]

SPARC port is killed with a sigbus error when building any module. This was due to an unaligned load in IntegerExp::toInteger from inside interpret() where UnionExp is prevalent.

The reason is because real_t may itself be a struct that is not suitably aligned for accessing dinteger_t (8-bytes).

Just waiting to hear back that this is fine, otherwise the corrective action would be to add a dinteger_t field so that UnionExp is suitably aligned for both native real_t and dinteger_t types.

It would be nice if dmc++ supported __attribute__(aligned(8))) instead of having this here...

[dlang-bot]

Thanks for your pull request, @ibuclaw!

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[thewilsonator]

Wont real be overkill in terms of alignment then if dinteger_t will do?

[WalterBright]

DMC++ supports pragma pack(8);

https://www.digitalmars.com/ctg/pragmas.html#pack

[ibuclaw]

DMC++ supports pragma pack(8);

Heh... Let's do that then. :-)

[ibuclaw]

Warning, C++ headers will become ugly.

[thewilsonator]

@ibuclaw this is labelled c++ Port but is targeted to master, so which is it? ;)

[ibuclaw]

Wont real be overkill in terms of alignment then if dinteger_t will do?

UnionExp has both IntegerExp and RealExp, potentially either of the toInteger() or toReal() functions could use an instruction that has strict alignment requirements if dealing with native types. The highest common denominator should be used to avoid any problems with one or the other.

@ibuclaw this is labelled c++ Port but is targeted to master, so which is it? ;)

Whoops, C++ port will follow, as this is affecting gcc trunk. :-)

[ibuclaw]

Updated to use align(8) and whatever is the equivalent for the host C++ compiler.